U.S. patent application number 17/433839 was filed with the patent office on 2022-05-12 for permeability-enhancing flooding system for tight oil reservoirs, and preparation and use thereof.
The applicant listed for this patent is PetroChina Company Limited. Invention is credited to Bin Ding, Jingfeng Dong, Xiangfei Geng, Baoshan Guan, Jingjun Pan, Falin Wei, Baocheng Wu, Chunming Xiong, Youguo Yan.
Application Number | 20220145164 17/433839 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-12 |
United States Patent
Application |
20220145164 |
Kind Code |
A1 |
Ding; Bin ; et al. |
May 12, 2022 |
Permeability-enhancing flooding system for tight oil reservoirs,
and preparation and use thereof
Abstract
A permeability-enhancing flooding system for tight oil
reservoirs and preparation and use thereof are disclosed. The
permeability-enhancing flooding system is present in a state of
oil-in-water droplet and composed of a surfactant, an oil-soluble
substance and water, and has an outer phase that is an aqueous
solution containing the surfactant, and an inner phase that is the
oil-soluble substance; and the surfactant comprises one of nonionic
gemini surfactants and anionic gemini surfactants, or a combination
of two or more thereof. The preparation process for the
permeability-enhancing flooding system is simple to operate,
suitable for industrialized production, and low in overall cost,
and has obvious application prospects in the field of tight oil
reservoirs for an enhanced oil recovery.
Inventors: |
Ding; Bin; (Beijing City,
CN) ; Xiong; Chunming; (Beijing City, CN) ;
Geng; Xiangfei; (Beijing City, CN) ; Guan;
Baoshan; (Beijing City, CN) ; Wei; Falin;
(Beijing City, CN) ; Pan; Jingjun; (Beijing City,
CN) ; Wu; Baocheng; (Beijing City, CN) ; Dong;
Jingfeng; (Beijing City, CN) ; Yan; Youguo;
(Beijing City, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PetroChina Company Limited |
Beijing |
|
CN |
|
|
Appl. No.: |
17/433839 |
Filed: |
October 29, 2020 |
PCT Filed: |
October 29, 2020 |
PCT NO: |
PCT/CN2020/124636 |
371 Date: |
August 25, 2021 |
International
Class: |
C09K 8/584 20060101
C09K008/584; E21B 43/16 20060101 E21B043/16 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 20, 2019 |
CN |
201911139683.8 |
Claims
1. A permeability-enhancing flooding system for tight oil
reservoirs, which is composed of a surfactant, an oil-soluble
substance and water, and present in a state of oil-in-water
droplet, and has an external phase that is an aqueous solution
containing the surfactant, and an inner phase that is the
oil-soluble substance; wherein the surfactant comprises one of
nonionic gemini surfactants and anionic gemini surfactants, or a
combination of two or more thereof; the nonionic gemini surfactant
is di-substituted diphenyl ether dicarboxylate having a structural
formula of: ##STR00007## wherein R is a carboxyl group, an amino
group, an ester group, an alkyl polyoxyethylene ether segment or an
alkylphenol polyoxyethylene ether segment; R' is a C.sub.9-12 alkyl
group; the anionic surfactant is tetraalkyl-substituted diphenyl
ether sulfonate having a structural formula of; ##STR00008##
wherein R'' is a C.sub.14-16 alkyl group; and the oil-soluble
substance is one of linear olefin and cinene, or a combination of
two or more thereof.
2.-5. (canceled)
6. The permeability-enhancing flooding system according to claim 1,
wherein the oil-soluble substance is undecane or cinene.
7. The permeability-enhancing flooding system according to claim 1,
wherein the total concentration of the surfactant and the
oil-soluble substance in the permeability-enhancing flooding system
is 0.05 wt. %-0.3 wt. %, wherein the mass percentage of the
surfactants is 75%-85%, and the mass percentage of the oil-soluble
substance is 15%-25%.
8. The permeability-enhancing flooding system according to claim 1,
wherein the oil-in-water droplet has a particle size distribution
of 3 nm-30 nm.
9. The permeability-enhancing flooding system according to claim 1,
wherein the water is inorganic salt water, and the mass content of
the inorganic salt is 20% or less, based on the total mass of the
permeability-enhancing flooding system.
10. The permeability-enhancing flooding system according to claim
9, wherein the inorganic salt is sodium chloride or calcium
chloride.
11. A method for preparing the permeability-enhancing flooding
system according to claim 1, comprising: mixing the surfactant and
the oil-soluble substance uniformly to obtain a homogeneous mixture
solution; or mixing the surfactant, the oil-soluble substance, and
an aqueous solution containing an inorganic salt uniformly to
obtain a homogeneous mixture solution; and diluting the homogeneous
mixture solution with water or inorganic salt water to a working
concentration to obtain the permeability-enhancing flooding
system.
12. The method according to claim 11, wherein the mixing and
diluting are both carried out by stirring at 10 rpm-400 rpm.
13. Use of the permeability-enhancing flooding system according to
claim 1 in the exploitation of tight oil reservoirs and shale oil
reservoirs.
14. The permeability-enhancing flooding system according to claim
1, wherein R is --(OCH.sub.2CH.sub.2).sub.10O--.
Description
TECHNICAL FIELD
[0001] The invention belongs to the technical field of exploitation
of tight oil reservoirs, and specifically relates to a
permeability-enhancing flooding system for tight oil reservoirs and
its preparation and use.
BACKGROUND
[0002] The recoverable resources of unconventional crude oil (tight
oil, oil shale, shale oil, etc.) in China are huge. The new
reserves of low permeability, tight and shale oil in the past 5
years have accounted for 70%-80% of the proven reserves, and
gradually become an important strategic alternative resource for
oil and gas exploration and development. Unconventional reservoirs
such as tight and shale reservoirs in China have an average
permeability of less than 0.3 mD, a porosity of 6%-15%, with
micron-sized pores as the main oil storage space having an average
throat radius of less than 400 nm. The mobility of the fluid
reservoirs is poor and the saturation of the dynamic fluid is less
than 30%, which greatly affects the mining efficiency. The tight
oil reservoirs in Ordos, Songliao and Junggar basins in China have
extremely poor fluidity, with an average mobility of less than 0.2
mD/mPas, which is substantially the same as that of ultra-heavy
oil, making development difficult.
[0003] Aiming at the efficient development of the "sweet spot" of
tight/shale oil reservoirs, with the goal of "fracture-controlled
reserves", liquid systems such as linear vegetable gum and
slickwater, which have the characteristics of high efficiency in
carrying sand and reducing friction, are used to achieve the
project goals such as initiation, fracturing and extension, and
have played an extremely important role in the initial volumetric
reconstruction of unconventional resources. However, the average
hydrodynamic radius of linear vegetable gum and slickwater
molecules is larger than 500 nm, which is much larger than the
radius of tight and shale throats. The start-up pressure of water
injection is high, and it cannot effectively enter the pores of
micro-nano matrix, and it is impossible to continuously improve the
recovery of unconventional oil reservoirs.
[0004] In recent years, the recovery technology of
imbibition-replacement and energy replenishment has become a hot
spot in the national and international research of efficient
development of unconventional oil reservoirs. It mainly includes
surfactant huff-puff, carbon dioxide huff-puff and nanofluid
flooding, among which surfactant imbibition huff-puff as a
tight-oil technology has good applicability. Although it has been
applied in many tight oil fields (blocks) in North America, the
core of imbibition is to maximize the capillary action of the
injected medium. For water-wet reservoirs, the fluid injected after
reservoir reconstruction can effectively enter the water-wet
fracture or pore medium, and expand the swept volume of the wetting
phase. However, most of the reservoirs in the oil storage space are
relatively oil-wet, and the capillary force becomes capillary
resistance, which will inhibit the oil-water imbibition replacement
effect of the tight and shale matrix, and greatly reduce the degree
of recovery. Furthermore, the hydrodynamic sizes of the existing
surfactants and ion matching liquids are all in the micron level,
and a part of the surfactants and the oil phase are emulsified in
situ, which virtually increases the difficulty of the migration of
crude oil in the matrix; finally, the existing fluids focus on
improving the wettability of the reservoir in order to enhance the
imbibition effect, but does not substantially solve the technical
problem of low fluidity in crude oil reservoirs, and it is
difficult to substantially improve the oil recovery of tight/shale
reservoirs.
SUMMARY
[0005] In order to solve at least one of the above technical
problems, the present invention provides a permeability-enhancing
flooding system suitable for unconventional oil reservoirs such as
tight and shale reservoirs, and its preparation and use.
[0006] In order to achieve the above object, the technical
solutions as follows are proposed in the present invention.
[0007] The first aspect of the present invention provides a
permeability-enhancing flooding system for tight oil reservoirs,
which is composed of a surfactant, an oil-soluble substance and
water, and present in a state of oil-in-water droplet, and has an
external phase that is an aqueous solution containing the
surfactant, and an inner phase that is the oil-soluble
substance;
[0008] wherein the surfactant comprises one of nonionic gemini
surfactants and anionic gemini surfactants, or a combination of two
or more thereof.
[0009] In the present invention, preferably, the oil-soluble
substance is one of linear olefin, furan, thiophene, cinene, and
isoprene condensate, or a combination of two or more thereof.
Preferably, the oil-soluble substance is one of linear olefin and
cinene, or a combination of two or more thereof.
[0010] More preferably, the oil-soluble substance is undecene or
cinene.
[0011] In the present invention, preferably, the total
concentration of the surfactant and the oil-soluble substance in
the permeability-enhancing flooding system is 0.05 wt. %-0.3 wt. %,
preferably 0.1 wt. %-0.15 wt. %;
[0012] wherein the mass percentage of the surfactant is 75%-85%,
and the mass percentage of the oil phase substances is 15%-25%. The
total concentration of the surfactant and the oil-soluble substance
in the permeability-enhancing flooding system is also referred to
as working concentration or effective concentration in the present
invention; and the permeability-enhancing flooding system can be
diluted to this concentration during use.
[0013] In the present invention, preferably, the oil-in-water
droplets have a particle size distribution of 3 nm-30 nm, and have
good tolerance to monovalent sodium salt and divalent calcium salt.
The particle size change rate thereof is less than 5% within 90
days.
[0014] A preferable embodiment of the present invention provides a
nonionic permeability-enhancing flooding system, wherein the
surfactant is a nonionic gemini surfactant, and the nonionic gemini
surfactant includes di-substituted diphenyl ether dicarboxylate
having a specific structural formula as follows:
##STR00001##
[0015] wherein R is a carboxyl group, an amino group, an ester
group, an alkyl polyoxyethylene ether segment or an alkylphenol
polyoxyethylene ether segment; R' is a C.sub.9-12 alkyl group.
[0016] In this preferable embodiment, by adjusting the alkyl group
R' in di-substituted diphenyl ether dicarboxylate as the nonionic
gemini surfactant to a C.sub.9-12 alkyl group, and changing the
structure of the oil-soluble substance to olefins, the nonionic
permeability-enhancing flooding system can be self-emulsified
without addition of a solubilizer, and has six characteristics of
small size liquid, small size oil, high interfacial activity,
biphase wetting, demulsification/dehydration and anti-adsorption.
The synthesis steps of the nonionic gemini surfactants can be found
in patent application publication CN109851530A, and are composed of
acylating chlorination reaction and one-step esterification
reaction, which is mild in the reaction conditions, simple to
operate, and easy to separate and purify for the product. The
specific reaction mechanism is as follows.
##STR00002##
[0017] The synthesis includes steps of:
[0018] 1) subjecting 4,4'-diphenyl ether dicarboxylic acid to
acylating chlorination reaction to obtain 4,4'-oxybisbenzoic
chloride;
[0019] 2) subjecting 4,4'-oxybisbenzoic chloride to substitution
reaction with benzene derivatives to obtain the target product,
wherein R is a carboxyl group, an amino group, an ester group,
alkyl polyoxyethylene ether, alkylphenol polyoxyethylene ether, or
the like, and R' is a C.sub.9-12 alkyl group.
[0020] In a specific embodiment of the present invention, the
disubstituted diphenyl ether dicarboxylate is di(nonylphenol
polyoxyethylene ether)-substituted diphenyl ether dicarboxylate
with a structural formula of:
##STR00003##
[0021] In this specific embodiment, the oil-in-water droplets in
the nonionic permeability-enhancing flooding system has a particle
size of less than 30 nm, as confirmed by a wide-angle laser light
scattering. The micro-etching model confirms that the nonionic
permeability-enhancing flooding system can effectively weaken the
association between the various components of crude oil, produce an
effect of small-size oil, and increase the seepage capacity of the
crude oil reservoir under simulated reservoir conditions. Both the
microscopic swept volume and the displacement efficiency exceed
90%. The interfacial tension evaluation result confirms that the
equilibrium interfacial tension between the nonionic
permeability-enhancing flooding system and the simulated oil from
Jimsar, Xinjiang is 0.02 mN/m at 80.degree. C., showing obvious
superiority. The contact angle evaluation result confirms that the
nonionic permeability-enhancing flooding system has a biphase
wetting characteristic, and the contact angles with hydrophilic and
lipophilic interfaces are 46.6.degree. and 69.3.degree.,
respectively. The evaluation results of demulsification/dehydration
show that the nonionic permeability-enhancing flooding system can
effectively reduce the "water-in-oil" inverse emulsification
phenomenon of crude oil. At 80.degree. C., the
demulsification/dehydration rate after 5 hours can reach 88.9%, and
the apparent viscosity of crude oil can be reduced. The viscosity
reduction rate of crude Oil from lower sweet spot in Jimsar is up
to 80% in the temperature range of 30.degree. C.-70.degree. C.,
which effectively improves the flowability of crude oil.
[0022] A preferable embodiment of the present invention provides an
anionic permeability-enhancing flooding system, wherein the
surfactant is an anionic gemini surfactant including
tetraalkyl-substituted diphenyl ether sulfonate having a specific
structural formula as follows:
##STR00004##
[0023] wherein R'' is a C.sub.14-16 alkyl group.
[0024] In this preferable embodiment, by adjusting the alkyl group
R'' in tetraalkyl-substituted diphenyl ether sulfonate as the
anionic gemini surfactant in the anionic permeability-enhancing
flooding system to a C.sub.14-16 alkyl group, and changing the
structure of the oil-soluble substance to olefins, the anionic
permeability-enhancing flooding system can be self-emulsified
without addition of a solubilizer, and has six characteristics of
small size liquid, small size oil, high interfacial activity,
biphase wetting, demulsification/dehydration and anti-adsorption.
The synthesis steps of the anionic gemini surfactants can be found
in patent application publication CN109678720A, and are composed of
one-step amine alkylation reaction and one-step sulfonation
reaction, which is mild in the reaction conditions, simple to
operate, and easy to separate and purify for the product. The
specific reaction mechanism is as follows.
##STR00005##
[0025] wherein R'' is a C.sub.14-16 alkyl group.
[0026] The synthesis includes steps of:
[0027] 1) subjecting 4,4'-diaminodiphenyl ether and brominated
alkane to amine alkylation reaction to obtain
N,N,N',N'-tetraalkyl-substituted diphenyl ether;
[0028] 2) subjecting N,N,N',N'-tetraalkyl-substituted diphenyl
ether and concentrated sulfuric acid to sulfonation reaction to
obtain the target product of N,N,N',N'-tetraalkyl-substituted
diphenyl ether sulfonate.
[0029] In a specific embodiment of the present invention, the
anionic gemini surfactant is tetracetyl-substituted diphenyl ether
sulfonate having a structural formula of:
##STR00006##
[0030] In this specific embodiment, the anionic
permeability-enhancing flooding system is a homogeneous and
transparent "oil-in-water" like solution having a particle size
distribution of the solution droplets of less than 30 nm at the
working concentration. The water may be distilled water, deionized
water or inorganic salt water. The particle size of the solution
droplets remains stable for a long time, having a particle size
change rate of less than 5% within 90 days. The particle size of
the droplets in the anionic permeability-enhancing flooding system
is less than 30 nm, as confirmed by the wide-angle laser light
scattering. The micro-etching model confirms that the anionic
permeability-enhancing flooding system can effectively weaken the
association between the various components of crude oil, produce an
effect of small-size oil, and increase the seepage capacity of the
crude oil reservoir under simulated reservoir conditions. Both the
microscopic swept volume and the displacement efficiency exceed
90%. The interfacial tension evaluation result confirms that the
equilibrium interfacial tension between the anionic
permeability-enhancing flooding system and the simulated oil from
Jimsar, Xinjiang is 0.1 mN/m at 80.degree. C., showing obvious
superiority. The contact angle evaluation result confirms that the
anionic permeability-enhancing flooding system has a biphase
wetting characteristic, and the contact angles with hydrophilic and
lipophilic interfaces are 46.0.degree. and 63.9.degree.,
respectively. The evaluation results of demulsification/dehydration
show that the anionic permeability-enhancing flooding system can
effectively reduce the "water-in-oil" inverse emulsification
phenomenon of crude oil. At 80.degree. C., the
demulsification/dehydration rate after 5 hours can reach 84.4%, and
the apparent viscosity of crude oil can be reduced. The viscosity
reduction rate of crude oil from lower sweet spot in Jimsar is up
to 80% in the temperature range of 30.degree. C.-70.degree. C.,
which effectively improves the flowability of crude oil.
[0031] The permeability-enhancing flooding system of the present
invention is suitable for the permeability enhancement and oil
displacement of unconventional oil reservoirs such as tight or
shale reservoirs, so as to improve the recovery. In the present
invention, by adjusting the alkyl group in di-substituted diphenyl
ether dicarboxylate as the surfactant from octyl group to nonyl and
dodecyl groups, or adjusting the alkyl group in
tetraalkyl-substituted diphenyl ether sulfonate from dodecyl group
to cetyl group, and changing the structure of the oil-soluble
substance to olefins, the permeability-enhancing flooding system
can be self-emulsified without addition of a solubilizer, and has
six characteristics of small size liquid, small size oil, high
interfacial activity, biphase wetting, demulsification/dehydration
and anti-adsorption.
[0032] The permeability-enhancing flooding system of the present
invention can disperse the crude oil into small sizes during
migration process after encountering crude oil, and improve the
seepage capacity. It has high interfacial activity, with an
interfacial tension with the crude oil of up to a level of
10.sup.-2 mN/m, and an displacement efficiency of crude oil of more
than 90%. It has biphase wetting ability, with a contact angle with
hydrophilic and lipophilic interfaces of about
45.degree.-70.degree.. It has demulsification/dehydration ability,
can weaken the "water-in-oil" inverse emulsification phenomenon of
crude oil, and reduce the apparent viscosity of crude oil. It has
good anti-adsorption ability, with a particle size substantially
unchanged when adsorbed in the oil sands for 72 h.
[0033] According to a specific embodiment of the present invention,
the permeability-enhancing flooding system is a homogeneous and
transparent "oil-in-water" like solution, having a particle size
distribution of the solution droplets of less than 30 nm at the
working concentration. The water may be distilled water, deionized
water or inorganic salt water. The particle size of the solution
droplets remains stable for a long time, with a particle size
change rate of less than 5% within 90 days, where the "particle
size change rate" refers to the variation amplitude of the particle
size.
[0034] When the water is an inorganic salt water, the
permeability-enhancing flooding system further comprising an
inorganic salt in a mass content of 20% or less.
[0035] Preferably, the inorganic salt is sodium chloride or calcium
chloride.
[0036] The second aspect of the present invention provides a method
for preparing the above-mentioned permeability-enhancing flooding
system, comprising steps of:
[0037] S1. mixing the surfactant and the oil-soluble substance
uniformly to obtain a homogeneous mixture solution;
[0038] or mixing the surfactant, the oil-soluble substance, and an
aqueous solution containing an inorganic salt uniformly to obtain a
homogeneous mixture solution;
[0039] S2. diluting the homogeneous mixture solution with water or
inorganic salt water to a working concentration to obtain the
permeability-enhancing flooding system.
[0040] Preferably, the mixing and diluting are carried out by
stirring at 10 rpm-400 rpm, preferably 100 rpm.
[0041] In a preferable embodiment of the present invention, the
method for preparing the nonionic permeability-enhancing flooding
system includes the following steps:
[0042] 1) mixing di-substituted diphenyl ether dicarboxylate as the
nonionic gemini surfactant, the oil-soluble substance and water
uniformly under stirring until being completely dissolved to obtain
a homogeneous mixture solution;
[0043] 2) diluting the homogeneous mixture solution prepared in
step 1) with deionized water or inorganic salt water under stirring
to the working concentration (0.05 wt. %-0.3 wt. %, preferably 0.1
wt. %-0.15 wt. %) until being completely dissolved, to obtain a
nonionic permeability-enhancing flooding material for an improved
oil recovery.
[0044] In another preferable embodiment of the present invention,
the method for preparing the anionic permeability-enhancing
flooding system includes the following steps:
[0045] 1) mixing tetraalkyl-substituted diphenyl ether sulfonate as
the anionic gemini surfactant, the oil-soluble substance and water
uniformly under stirring until being completely dissolved to obtain
a homogeneous mixture solution;
[0046] 2) diluting the homogeneous mixture solution prepared in
step 1) with deionized water or inorganic salt water under stirring
to the working concentration (0.05 wt. %-0.3 wt. %, preferably 0.1
wt. %-0.15 wt. %) until being completely dissolved, to obtain an
anionic permeability-enhancing flooding material for an improved
oil recovery.
[0047] The third aspect of the present invention provides use of
the above-mentioned permeability-enhancing flooding system in the
exploitation of tight oil reservoirs and shale oil reservoirs.
[0048] As compared with the prior art, the present invention has
the following advantages and effects:
[0049] 1) Two types of gemini surfactants, di-substituted diphenyl
ether dicarboxylate and tetraalkyl-substituted diphenyl ether
sulfonate, and an oil-soluble substance are introduced in the
present invention to prepare nonionic and anionic
permeability-enhancing flooding systems with mild reaction
conditions and simple preparation process, which can be used for
industrial mass production, and completely solve the technical
difficulty of agglomeration tendency and poor stability of the
"oil-in-water" system under low-energy conditions.
[0050] 2) The nonionic and anionic permeability-enhancing flooding
systems obtained by the present invention have six characteristics:
it has a size of less than 30 nm, and thus have the ability to
enter the micro-nano pores of tight oil reservoirs; they can
effectively weaken the association between various components of
crude oil and produce an effect of small size oil, and increase the
seepage capacity of crude oil reservoirs under simulated reservoir
conditions; they have ultra-low interfacial tension and excellent
oil displacement ability; they have good wetting ability for both
hydrophilic and lipophilic reservoirs, and have good reservoir
applicability; they can effectively weaken the "water-in-oil"
inverse emulsification phenomenon of crude oil, reduce the apparent
viscosity of crude oil, and improve the flowability of crude oil;
they have good anti-adsorption ability, with a particle size
substantially unchanged when adsorbed in oil sands for 72
hours.
[0051] 3) The nonionic and anionic permeability-enhancing flooding
systems obtained by the present invention can be used in low
permeability reservoirs, ultra-low permeability reservoirs, tight
reservoirs and shale oil and gas to improve recovery, and have very
broad application prospects.
BRIEF DESCRIPTION OF DRAWINGS
[0052] FIG. 1 is a particle size distribution diagram of the
nonionic permeability-enhancing flooding system prepared in Example
1.
[0053] FIG. 2 is a representative photograph of the nonionic
permeability-enhancing flooding system prepared in Example 1, which
converts the simulated oil from Jimsar into "small-size oil".
[0054] FIG. 3 is a graph of interfacial tension between the
permeability-enhancing flooding system prepared in Examples 1 to 4
and the simulated oil from Jimsar.
[0055] FIG. 4 is the contact angle between the nonionic
permeability-enhancing flooding system prepared in Example 1 and
the hydrophilic interface of SiO.sub.2.
[0056] FIG. 5 is the contact angle between the nonionic
permeability-enhancing flooding system prepared in Example 1 and
the lipophilic interface of SiO.sub.2.
[0057] FIG. 6 shows the demulsification/dehydration effect of the
permeability-enhancing flooding system prepared in Examples 1 to 4
with the "water-in-oil" crude oil from lower sweet spot in
Jimsar.
[0058] FIG. 7 shows the viscosity reduction effect of the
permeability-enhancing flooding system prepared in Examples 1 to 4
with the "water-in-oil" crude oil from lower sweet spot in
Jimsar.
[0059] FIG. 8 shows the particle size changes of the
permeability-enhancing flooding system prepared in Examples 1 to 4
after adsorbed in the oil sands for different periods of time.
[0060] FIG. 9 is a particle size distribution diagram of the
anionic permeability-enhancing flooding system prepared in Example
2.
[0061] FIG. 10 is a representative photograph of the anionic
permeability-enhancing flooding system prepared in Example 2, which
converts the simulated oil from Jimsar into "small-size oil".
[0062] FIG. 11 is the contact angle between the anionic
permeability-enhancing flooding system prepared in Example 2 and
the hydrophilic interface of SiO.sub.2.
[0063] FIG. 12 is the contact angle between the anionic
permeability-enhancing flooding system prepared in Example 2 and
the lipophilic interface of SiO.sub.2.
[0064] FIG. 13 is a particle size distribution diagram of the
nonionic permeability-enhancing flooding system prepared in Example
3.
[0065] FIG. 14 is a representative photograph of the nonionic
permeability-enhancing flooding system prepared in Example 3, which
converts the simulated oil from Jimsar into "small-size oil".
[0066] FIG. 15 is the contact angle between the nonionic
permeability-enhancing flooding system prepared in Example 3 and
the hydrophilic interface of SiO.sub.2.
[0067] FIG. 16 is the contact angle between the nonionic
permeability-enhancing flooding system prepared in Example 3 and
the lipophilic interface of SiO.sub.2.
[0068] FIG. 17 is a particle size distribution diagram of the
anionic permeability-enhancing flooding system prepared in Example
4.
[0069] FIG. 18 is a representative photograph of the anionic
permeability-enhancing flooding system prepared in Example 4, which
converts the simulated oil from Jimsar into "small-size oil".
[0070] FIG. 19 is the contact angle between the anionic
permeability-enhancing flooding system prepared in Example 4 and
the hydrophilic interface of SiO.sub.2.
[0071] FIG. 20 is the contact angle between the anionic
permeability-enhancing flooding system prepared in Example 4 and
the lipophilic interface of SiO.sub.2.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0072] In order to explain the present invention more clearly, the
present invention will be further described with reference to
preferred embodiments. Those skilled in the art should understand
that the content described below is illustrative rather than
restrictive, and should not limit the protection scope of the
present invention.
Example 1
[0073] This Example provides a nonionic permeability-enhancing
flooding system and a preparation method thereof comprising main
steps as follows.
[0074] 1. Preparation of a nonionic gemini surfactant,
di(nonylphenol polyoxyethylene ether)-substituted diphenyl ether
dicarboxylate
[0075] 4,4'-diphenyl ether dicarboxylic acid was subjected to
acylating chlorination reaction to obtain 4,4'-oxybisbenzoic
chloride;
[0076] 4,4'-oxybisbenzoic chloride and nonylphenol polyoxyethylene
ether were subjected to esterification to obtain the target
product, di(nonylphenol polyoxyethylene ether)-substituted diphenyl
ether dicarboxylate.
[0077] In this synthesis route, the starting material 4,4'-diphenyl
ether dicarboxylic acid was activated by acylating chlorination to
obtain the intermediate acyl-chloride product; then the acyl
chloride was esterified with nonylphenol polyoxyethylene ether as
an surfactant so that two molecules of nonylphenol polyoxyethylene
ether were connected to two symmetric positions of diphenyl ether
to obtain the target product, di(nonylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate as the nonionic
surfactant.
[0078] 2. Preparation of nonionic permeability-enhancing flooding
system
[0079] (1) 5 parts by weight of sodium chloride, 15 parts by weight
of undecene, 60 parts of di(nonylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate as the nonionic
gemini surfactant, and 20 parts of water were weighed, placed into
a reactor, and mixed under stirring at 100 rpm until completely
dissolved, to give a homogeneous mixture solution.
[0080] (2) 0.15 part by weight of the above homogeneous mixture
solution and 99.8 parts by weight of water were weighed, placed
into a reactor, and mixed under stirring at 100 rpm until
completely dissolved, to obtain a nonionic permeability-enhancing
flooding system having an effective concentration of 0.11%, a
homogeneous and transparent appearance, and being stable for a long
time. The preparation method of the nonionic permeability-enhancing
flooding system uses mild conditions and simple preparation
process, can be used for industrial mass production, and completely
solves the technical difficulty of easy agglomeration and poor
stability of the "oil-in-water" system under low-energy
conditions.
[0081] The following inspections and tests were carried out on the
nonionic permeability-enhancing flooding system.
[0082] As measured by dynamic light scattering (BI-200SM,
Brookhaven) at 25.degree. C. and a scattering angle of 90.degree.,
the nonionic permeability-enhancing flooding system had an average
particle size of 10.1 nm (see FIG. 1), and thus has a capacity of
entering micro-nano pores of tight oil reservoirs.
[0083] As determined by a self-built platform with integrated
micro-etching model (size 1.5 cm.times.1.5 cm, pore depth 15 .mu.m,
throat depth 2 .mu.m), micro-nano-scale displacement platform, and
optical microscope (Leica M165FC), at 25.degree. C., the
above-mentioned nonionic permeability-enhancing flooding system can
convert a simulated oil from Jimsar, Xinjiang (having a volume
ratio of Jimsar crude oil to kerosene of 10:4, and a viscosity of
63.4 mPas at 50.degree. C.) into "small size oil" (see FIG. 2). It
shows that the nonionic permeability-enhancing flooding system can
effectively weaken the association between the various components
of crude oil, produce an effect of small-size oil, and increase the
seepage capacity of the crude oil reservoir under simulated
reservoir conditions.
[0084] As measured by Spinning Drop Interface tensiometer, the
equilibrium interfacial tension between the above-mentioned
nonionic permeability-enhancing flooding system and the simulated
oil from Jimsar, Xinjiang is 0.02 mN/m at 80.degree. C. and 6000
rpm (see FIG. 3). It shows that the nonionic permeability-enhancing
flooding system has ultra-low interfacial tension and excellent oil
displacement ability.
[0085] As measured by Dataphysics contact angle tester, the contact
angle between the nonionic permeability-enhancing flooding system
and the hydrophilic interface of SiO.sub.2 is 46.6.degree. (see
FIG. 4), and the contact angle with the lipophilic interface of
SiO.sub.2 is 69.3.degree. (See FIG. 5), at 25.degree. C. It shows
that the nonionic permeability-enhancing flooding system has good
wetting ability for both hydrophilic and lipophilic reservoirs, and
has good reservoir applicability.
[0086] When 7.5 mg of the above-mentioned nonionic
permeability-enhancing flooding system is added to 10 g of
"water-in-oil" crude oil from lower sweet spot in Jimsar at
80.degree. C., the demulsification/dehydration rate after 5 hours
can reach 88.9% (see FIG. 6). As measured by RS600 rheometer, the
above-mentioned nonionic permeability-enhancing flooding material
for an improved recovery has a viscosity reduction rate of 80% or
more for the "water-in-oil" crude oil from lower sweet spot in
Jimsar, at 30.degree. C., 40.degree. C., 50.degree. C., 60.degree.
C., or 70.degree. C. (see FIG. 7). It shows that the nonionic
permeability-enhancing flooding system can effectively reduce the
"water-in-oil" inverse emulsification phenomenon of crude oil,
reduce the apparent viscosity of crude oil, and improve the
flowability of crude oil.
[0087] 150 g of the above-mentioned nonionic permeability-enhancing
flooding system is mixed with 10 g of oil sands and shaken at
80.degree. C. for different periods of time, and the supernatant
liquid is taken to determine the particle size. After 72 hours of
adsorption, the particle size of the nonionic
permeability-enhancing flooding system is substantially unchanged,
about 10 nm (see FIG. 8). It shows that the nonionic
permeability-enhancing flooding system has good anti-adsorption
ability, and the particle size is substantially unchanged when
adsorbed in the oil sands for 72 h.
Example 2
[0088] This Example provides an anionic permeability-enhancing
flooding system and a preparation method thereof comprising main
steps as follows.
[0089] 1. Preparation of a gemini surfactant,
N,N,N',N'-tetracetyl-substituted diphenyl ether sulfonate
[0090] 4,4'-diaminodiphenyl ether and brominated hexadecane were
subjected to amine alkylation reaction to obtain
N,N,N',N'-tetracetyl-substituted diphenyl ether;
[0091] N,N,N',N'-tetracetyl-substituted diphenyl ether and
concentrated sulfuric acid were subjected to sulfonation reaction
to obtain the target product, N,N,N',N'-tetraalkyl-substituted
diphenyl ether sulfonate.
[0092] 2. Preparation of aonionic permeability-enhancing flooding
system
[0093] (1) 1 parts by weight of calcium chloride, 15 parts by
weight of cinene, 65 parts of tetracetyl-substituted diphenyl ether
sulfonate as the gemini surfactant, and 19 parts of water were
weighed, placed into a reactor, and mixed under stirring at 200 rpm
until completely dissolved, to give a homogeneous mixture
solution.
[0094] (2) 0.2 part by weight of the above homogeneous mixture
solution and 95 parts by weight of water were weighed, placed into
a reactor, and mixed under stirring at 200 rpm until completely
dissolved, to obtain an anionic permeability-enhancing flooding
material for an improved recovery, having an effective
concentration of 0.17%, a homogeneous and transparent appearance,
and being stable for a long time. The preparation method of the
anionic permeability-enhancing flooding system uses mild conditions
and simple preparation process, can be used for industrial mass
production, and completely solves the technical difficulty of easy
agglomeration and poor stability of the "oil-in-water" system under
low-energy conditions.
[0095] The following inspections and tests were carried out on the
anionic permeability-enhancing flooding system.
[0096] As measured by dynamic light scattering (BI-200SM,
Brookhaven) at 25.degree. C. and a scattering angle of 90.degree.,
the anionic permeability-enhancing flooding system had an average
particle size of 11.3 nm (see FIG. 9), and thus has a capacity of
entering micro-nano pores of tight oil reservoirs.
[0097] As determined by a self-built platform with integrated
micro-etching model (size 1.5 cm.times.1.5 cm, pore depth 15 .mu.m,
throat depth 2 .mu.m), micro-nano-scale displacement platform, and
optical microscope (Leica M165FC), at 25.degree. C., the
above-mentioned anionic permeability-enhancing flooding system can
convert a simulated oil from Jimsar, Xinjiang (having a volume
ratio of Jimsar crude oil to kerosene of 10:4, and a viscosity of
63.4 mPas at 50.degree. C.) into "small size oil" (see FIG. 10). It
shows that the anionic permeability-enhancing flooding system can
effectively weaken the association between the various components
of crude oil, produce an effect of small-size oil, and increase the
seepage capacity of the crude oil reservoir under simulated
reservoir conditions.
[0098] As measured by Spinning Drop Interface tensiometer, the
equilibrium interfacial tension between the above-mentioned anionic
permeability-enhancing flooding system and the simulated oil from
Jimsar, Xinjiang is 0.1 mN/m at 80.degree. C. and 6000 rpm (see
FIG. 3). It shows that the anionic permeability-enhancing flooding
system has ultra-low interfacial tension and excellent oil
displacement ability.
[0099] As measured by Dataphysics contact angle tester, the contact
angle between the anionic permeability-enhancing flooding system
and the hydrophilic interface of SiO.sub.2 is 46.0.degree. (see
FIG. 11), and the contact angle with the lipophilic interface of
SiO.sub.2 is 63.9.degree. (See FIG. 12), at 25.degree. C. It shows
that the anionic permeability-enhancing flooding system has good
wetting ability for both hydrophilic and lipophilic reservoirs, and
has good reservoir applicability.
[0100] When 7.5 mg of the above-mentioned anionic
permeability-enhancing flooding system is added to 10 g of
"water-in-oil" crude oil from lower sweet spot in Jimsar at
80.degree. C., the demulsification/dehydration rate after 5 hours
can reach 84.4% (see FIG. 6). As measured by RS600 rheometer, the
above-mentioned anionic permeability-enhancing flooding system has
a viscosity reduction rate of 80% or more for the "water-in-oil"
crude oil from lower sweet spot in Jimsar, at 30.degree. C.,
40.degree. C., 50.degree. C., 60.degree. C., or 70.degree. C. (see
FIG. 7). It shows that the anionic permeability-enhancing flooding
system can effectively reduce the "water-in-oil" inverse
emulsification phenomenon of crude oil, reduce the apparent
viscosity of crude oil, and improve the flowability of crude
oil.
[0101] 150 g of the above-mentioned anionic permeability-enhancing
flooding system is mixed with 10 g of oil sands and shaken at
80.degree. C. for different periods of time, and the supernatant
liquid is taken to determine the particle size. After 72 hours of
adsorption, the particle size of the anionic permeability-enhancing
flooding system is substantially unchanged, about 15-20 nm (see
FIG. 8). It shows that the anionic permeability-enhancing flooding
system has good anti-adsorption ability, and the particle size is
substantially unchanged when adsorbed in the oil sands for 72
h.
Example 3
[0102] This Example provides a nonionic permeability-enhancing
flooding system and a preparation method thereof comprising main
steps as follows.
[0103] 1. Preparation of a nonionic gemini surfactant,
di(dodecylphenol polyoxyethylene ether)-substituted diphenyl ether
dicarboxylate
[0104] 4,4'-diphenyl ether dicarboxylic acid was subjected to
acylating chlorination reaction to obtain 4,4'-oxybisbenzoic
chloride;
[0105] 4,4'-oxybisbenzoic chloride and dodecylphenol
polyoxyethylene ether were subjected to esterification to obtain
the target product, di(dodecylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate.
[0106] In this synthesis route, the starting material 4,4'-diphenyl
ether dicarboxylic acid was activated by acylating chlorination to
obtain the intermediate acyl-chloride product; then the acyl
chloride was esterified with dodecylphenol polyoxyethylene ether as
an surfactant so that two molecules of dodecylphenol
polyoxyethylene ether were connected to two symmetric positions of
diphenyl ether to obtain the target product, di(dodecylphenol
polyoxyethylene ether)-substituted diphenyl ether dicarboxylate, as
the nonionic surfactant.
[0107] 2. Preparation of nonionic permeability-enhancing flooding
system
[0108] (1) 5 parts by weight of sodium chloride, 15 parts by weight
of undecene, 60 parts of di(dodecylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate as the nonionic
gemini surfactant, and 20 parts of water were weighed, placed into
a reactor, and mixed under stirring at 100 rpm until completely
dissolved, to give a homogeneous mixture solution.
[0109] (2) 0.15 part by weight of the above homogeneous mixture
solution and 99.8 parts by weight of water were weighed, placed
into a reactor, and mixed under stirring at 100 rpm until
completely dissolved, to obtain a nonionic permeability-enhancing
flooding system having an effective concentration of 0.11%, a
homogeneous and transparent appearance, and being stable for a long
time. The preparation method of the nonionic permeability-enhancing
flooding system uses mild conditions and simple preparation
process, can be used for industrial mass production, and completely
solves the technical difficulty of easy agglomeration and poor
stability of the "oil-in-water" system under low-energy
conditions.
[0110] The following inspections and tests were carried out on the
nonionic permeability-enhancing flooding system.
[0111] As measured by dynamic light scattering (BI-200SM,
Brookhaven) at 25.degree. C. and a scattering angle of 90.degree.,
the nonionic permeability-enhancing flooding system had an average
particle size of 11.1 nm (see FIG. 13), and thus has a capacity of
entering micro-nano pores of tight oil reservoirs.
[0112] As determined by a self-built platform with integrated
micro-etching model (size 1.5 cm.times.1.5 cm, pore depth 15 throat
depth 2 .mu.m), micro-nano-scale displacement platform, and optical
microscope (Leica M165FC), at 25.degree. C., the above-mentioned
nonionic permeability-enhancing flooding system can convert a
simulated oil from Jimsar, Xinjiang (having a volume ratio of
Jimsar crude oil to kerosene of 10:4, and a viscosity of 63.4 mPas
at 50.degree. C.) into "small size oil" (see FIG. 14). It shows
that the nonionic permeability-enhancing flooding system can
effectively weaken the association between the various components
of crude oil, produce an effect of small-size oil, and increase the
seepage capacity of the crude oil reservoir under simulated
reservoir conditions.
[0113] As measured by Spinning Drop Interface tensiometer, the
equilibrium interfacial tension between the above-mentioned
nonionic permeability-enhancing flooding system and the simulated
oil from Jimsar, Xinjiang is 0.025 mN/m at 80.degree. C. and 6000
rpm (see FIG. 3). It shows that the nonionic permeability-enhancing
flooding system has ultra-low interfacial tension and excellent oil
displacement ability.
[0114] As measured by Dataphysics contact angle tester, the contact
angle between the nonionic permeability-enhancing flooding system
and the hydrophilic interface of SiO.sub.2 is 45.1.degree. (see
FIG. 15), and the contact angle with the lipophilic interface of
SiO.sub.2 is 45.5.degree. (See FIG. 16), at 25.degree. C. It shows
that the nonionic permeability-enhancing flooding system has good
wetting ability for both hydrophilic and lipophilic reservoirs, and
has good reservoir applicability.
[0115] When 7.5 mg of the above-mentioned nonionic
permeability-enhancing flooding system is added to 10 g of
"water-in-oil" crude oil from lower sweet spot in Jimsar at
80.degree. C., the demulsification/dehydration rate after 5 hours
can reach 84.4% (see FIG. 6). As measured by RS600 rheometer, the
above-mentioned nonionic permeability-enhancing flooding material
for an improved recovery has a viscosity reduction rate of 80% or
more for the "water-in-oil" crude oil from lower sweet spot in
Jimsar, at 30.degree. C., 40.degree. C., 50.degree. C., 60.degree.
C., or 70.degree. C. (see FIG. 7). It shows that the nonionic
permeability-enhancing flooding system can effectively reduce the
"water-in-oil" inverse emulsification phenomenon of crude oil,
reduce the apparent viscosity of crude oil, and improve the
flowability of crude oil.
[0116] 150 g of the above-mentioned nonionic permeability-enhancing
flooding system is mixed with 10 g of oil sands and shaken at
80.degree. C. for different periods of time, and the supernatant
liquid is taken to determine the particle size. After 72 hours of
adsorption, the particle size of the nonionic
permeability-enhancing flooding system is substantially unchanged,
about 10 nm (see FIG. 8). It shows that the nonionic
permeability-enhancing flooding system has good anti-adsorption
ability, and the particle size is substantially unchanged when
adsorbed in the oil sands for 72 h.
Example 4
[0117] This Example provides an anionic permeability-enhancing
flooding system and a preparation method thereof comprising main
steps as follows.
[0118] 1. Preparation of a gemini surfactant,
N,N,N',N'-tetramyristyl-substituted diphenyl ether sulfonate
[0119] 4,4'-diaminodiphenyl ether and brominated tetradecane were
subjected to amine alkylation reaction to obtain
N,N,N',N'-tetramyristyl-substituted diphenyl ether;
[0120] N,N,N',N'-tetramyristyl-substituted diphenyl ether and
concentrated sulfuric acid were subjected to sulfonation reaction
to obtain the target product, N,N,N',N'-tetramyristyl-substituted
diphenyl ether sulfonate.
[0121] 2. Preparation of aonionic permeability-enhancing flooding
system
[0122] (1) 1 parts by weight of calcium chloride, 15 parts by
weight of cinene, 65 parts of tetramyristyl-substituted diphenyl
ether sulfonate as the gemini surfactant, and 19 parts of water
were weighed, placed into a reactor, and mixed under stirring at
200 rpm until completely dissolved, to give a homogeneous mixture
solution.
[0123] (2) 0.2 part by weight of the above homogeneous mixture
solution and 95 parts by weight of water were weighed, placed into
a reactor, and mixed under stirring at 200 rpm until completely
dissolved, to obtain an anionic permeability-enhancing flooding
material for an improved recovery, having an effective
concentration of 0.17%, a homogeneous and transparent appearance,
and being stable for a long time. The preparation method of the
anionic permeability-enhancing flooding system uses mild conditions
and simple preparation process, can be used for industrial mass
production, and completely solves the technical difficulty of easy
agglomeration and poor stability of the "oil-in-water" system under
low-energy conditions.
[0124] The following inspections and tests were carried out on the
anionic permeability-enhancing flooding system.
[0125] As measured by dynamic light scattering (BI-200SM,
Brookhaven) at 25.degree. C. and a scattering angle of 90.degree.,
the anionic permeability-enhancing flooding system had an average
particle size of 7.5 nm (see FIG. 17), and thus has a capacity of
entering micro-nano pores of tight oil reservoirs.
[0126] As determined by a self-built platform with integrated
micro-etching model (size 1.5 cm.times.1.5 cm, pore depth 15 .mu.m,
throat depth 2 .mu.m), micro-nano-scale displacement platform, and
optical microscope (Leica M165FC), at 25.degree. C., the
above-mentioned anionic permeability-enhancing flooding system can
convert a simulated oil from Jimsar, Xinjiang (having a volume
ratio of Jimsar crude oil to kerosene of 10:4, and a viscosity of
63.4 mPas at 50.degree. C.) into "small size oil" (see FIG. 18). It
shows that the anionic permeability-enhancing flooding system can
effectively weaken the association between the various components
of crude oil, produce an effect of small-size oil, and increase the
seepage capacity of the crude oil reservoir under simulated
reservoir conditions.
[0127] As measured by Spinning Drop Interface tensiometer, the
equilibrium interfacial tension between the above-mentioned anionic
permeability-enhancing flooding system and the simulated oil from
Jimsar, Xinjiang is 0.13 mN/m at 80.degree. C. and 6000 rpm (see
FIG. 3). It shows that the anionic permeability-enhancing flooding
system has ultra-low interfacial tension and excellent oil
displacement ability.
[0128] As measured by Dataphysics contact angle tester, the contact
angle between the anionic permeability-enhancing flooding system
and the hydrophilic interface of SiO.sub.2 is 45.7.degree. (see
FIG. 19), and the contact angle with the lipophilic interface of
SiO.sub.2 is 43.0.degree. (See FIG. 20), at 25.degree. C. It shows
that the anionic permeability-enhancing flooding system has good
wetting ability for both hydrophilic and lipophilic reservoirs, and
has good reservoir applicability.
[0129] When 7.5 mg of the above-mentioned anionic
permeability-enhancing flooding system is added to 10 g of
"water-in-oil" crude oil from lower sweet spot in Jimsar at
80.degree. C., the demulsification/dehydration rate after 5 hours
can reach 62.2% (see FIG. 6). As measured by RS600 rheometer, the
above-mentioned anionic permeability-enhancing flooding system has
a viscosity reduction rate of 80% or more for the "water-in-oil"
crude oil from lower sweet spot in Jimsar, at 30.degree. C.,
40.degree. C., 50.degree. C., 60.degree. C., or 70.degree. C. (see
FIG. 7). It shows that the anionic permeability-enhancing flooding
system can effectively reduce the "water-in-oil" inverse
emulsification phenomenon of crude oil, reduce the apparent
viscosity of crude oil, and improve the flowability of crude
oil.
[0130] 150 g of the above-mentioned anionic permeability-enhancing
flooding system is mixed with 10 g of oil sands and shaken at
80.degree. C. for different periods of time, and the supernatant
liquid is taken to determine the particle size. After 72 hours of
adsorption, the particle size of the anionic permeability-enhancing
flooding system is substantially unchanged, about 10 nm (see FIG.
8). It shows that the anionic permeability-enhancing flooding
system has good anti-adsorption ability, and the particle size is
substantially unchanged when adsorbed in the oil sands for 72
h.
Comparative Example 1
[0131] This Comparative Example provides a nonionic
permeability-enhancing flooding system and a preparation method
thereof comprising main steps as follows.
[0132] (1) 5 parts by weight of sodium chloride, 15 parts by weight
of undecene, 60 parts of di(octylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate as the nonionic
gemini surfactant, and 20 parts of water were weighed, placed into
a reactor, and mixed under stirring at 100 rpm until completely
dissolved, to give a homogeneous mixture solution.
[0133] (2) 0.15 part by weight of the above homogeneous mixture
solution and 99.8 parts by weight of water were weighed, placed
into a reactor, and mixed under stirring at 100 rpm until
completely dissolved, to obtain a nonionic permeability-enhancing
flooding system having an effective concentration of 0.11%, and a
homogeneous and transparent appearance.
[0134] The following inspections and tests were carried out on the
nonionic permeability-enhancing flooding system.
[0135] The average particle size of the above-mentioned nonionic
permeability-enhancing flooding system was measured by dynamic
light scattering (BI-200SM, Brookhaven) at 25.degree. C. and a
scattering angle of 90.degree.. The data from the instrument did
not converge, indicating a failure to form the desired nanoscale
system. As compared with Example 1, this Comparative Example has
changed the surfactant to di(octylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate as the nonionic
gemini surfactant, but the desired nanoscale system is not formed,
indicating that the desired nanoscale system cannot be obtained
without addition of a solubilizer, if the alkyl chain in the
nonionic gemini surfactant is changed.
Comparative Example 2
[0136] This Comparative Example provides an anionic
permeability-enhancing flooding system and a preparation method
thereof comprising main steps as follows.
[0137] (1) 1 parts by weight of calcium chloride, 15 parts by
weight of cinene, 65 parts of tetralauryl-substituted diphenyl
ether sulfonate as the gemini surfactant, and 19 parts of water
were weighed, placed into a reactor, and mixed under stirring at
200 rpm until completely dissolved, to give a homogeneous mixture
solution.
[0138] (2) 0.2 part by weight of the above homogeneous mixture
solution and 95 parts by weight of water were weighed, placed into
a reactor, and mixed under stirring at 200 rpm until completely
dissolved, to obtain an anionic permeability-enhancing flooding
material for an improved recovery, having an effective
concentration of 0.17%, a homogeneous and transparent appearance,
and stable for a long time.
[0139] The following inspections and tests were carried out on the
anionic permeability-enhancing flooding system.
[0140] The average particle size of the above-mentioned anionic
permeability-enhancing flooding system was measured by dynamic
light scattering (BI-200SM, Brookhaven) at 25.degree. C. and a
scattering angle of 90.degree.. The data from the instrument did
not converge, indicating a failure to form the desired nanoscale
system. As compared with Example 2, this Comparative Example has
changed the surfactant to tetralauryl-substituted diphenyl ether
sulfonate as the gemini surfactant, but the desired nanoscale
system is not formed, indicating that the desired nanoscale system
cannot be obtained without addition of a solubilizer, if the alkyl
chain in the anionic gemini surfactant is changed.
Comparative Example 3
[0141] This Comparative Example provides a nonionic
permeability-enhancing flooding system and a preparation method
thereof comprising main steps as follows.
[0142] (1) 5 parts by weight of sodium chloride, 15 parts by weight
of xylene, 60 parts of di(nonylphenol polyoxyethylene
ether)-substituted diphenyl ether dicarboxylate as the nonionic
gemini surfactant, and 20 parts of water were weighed, placed into
a reactor, and mixed under stirring at 100 rpm until completely
dissolved, to give a homogeneous mixture solution.
[0143] (2) 0.15 part by weight of the above homogeneous mixture
solution and 99.8 parts by weight of water were weighed, placed
into a reactor, and mixed under stirring at 100 rpm until
completely dissolved, to obtain a nonionic permeability-enhancing
flooding system having an effective concentration of 0.11%, a
homogeneous and transparent appearance, and being stable for a long
time.
[0144] The following inspections and tests were carried out on the
nonionic permeability-enhancing flooding system.
[0145] The average particle size of the above-mentioned nonionic
permeability-enhancing flooding system was measured by dynamic
light scattering (BI-200SM, Brookhaven) at 25.degree. C. and a
scattering angle of 90.degree.. The data from the instrument did
not converge, indicating a failure to form the desired nanoscale
system. As compared with Example 1, this Comparative Example has
changed the oil-soluble substance to xylene, but the desired
nanoscale system is not formed. It shows that the desired nanoscale
system cannot be obtained without addition of the solubilizer, when
the oil-soluble substance is changed. As seen from the above
Comparative Examples 1-3, in the permeability-enhancing flooding
system of the present invention, the three components are
synergistically interacting with each other, and the desired
nanoscale system cannot be obtained when any one is out of the
defined scope in the present invention.
[0146] Obviously, the above-mentioned examples of the present
invention are merely examples for clearly illustrating the present
invention, and are not intended to limit the embodiments of the
present invention. For those of ordinary skill in the art, other
different forms of modifications or changes can be made on the
basis of the above description. It is impossible to be exhaust all
of the embodiments herein. Any obvious modifications or changes
derived from the technical solutions of the present invention are
still within the protection scope of the present invention.
* * * * *